TRANSIENT BEHAVIOR AND ANALYSIS OF NON DARCY FLOW IN POROUS AND FRACTURED RESERVOIRS ACCORDING TO THE BARREE AND CONWAY MODEL

This study introduces the usage of the Barree and Conway flow model in well test analysis of a single‑phase non‑Darcy flow in porous and fractured reservoirs. The non‑Darcy flow behavior is handled using a numerical model incorporating the non‑Darcy flow effects according to the Barree and Conway model. The developed numerical model is capable of simulating all near wellbore effects, such as wellbore storage and skin effects under non‑Darcy flow condition. A steady‑state non‑Darcy radial flow solution is also derived to verify the numerical simulation results. The numerical model is used to interpret radial flow pressure‑transient responses for pressure buildup and drawdown well tests. In simulated pressure drawdown tests with non‑Darcy flow with no skin and wellbore storage effects, the permeability, obtained using the standard straight‑line analysis, is an apparent permeability and not the Darcy's constant permeability. The estimated permeability ranges from the minimum permeability and to less than the Darcy's permeability. Thus in pressure drawdown tests the standard straight‑line analysis techniques underestimate the Darcy's permeability when non‑Darcy flow exists. A pressure buildup test, following non‑Darcy flow drawdown tests, may be good for determining Darcy's permeability values using standard straight‑line analysis without significant non‑Darcy flow. The Barree and Conway non‑Darcy model parameters may not be directly estimated from pressure‑transient well tests. However, it can be estimated by a matching process using the generated type curves from the developed numerical model. The type curves are provided to demonstrate a methodology for modeling single phase non‑Darcy flow effects in porous and fractured rocks. The developed numerical model is used to interpret several actual well tests from single‑phase high rate wells in Kuwait.